From 56e4e3a3478ee9ff0bee3b01820cfe919f0454e6 Mon Sep 17 00:00:00 2001
From: ladyada <limor@ladyada.net>
Date: Mon, 10 Dec 2012 15:55:17 -0500
Subject: [PATCH] added SPI - tested works

---
 Adafruit_ADXL345.cpp | 101 +++++++++++++++++++++++++++++++++++--------
 Adafruit_ADXL345.h   |   7 +++
 2 files changed, 89 insertions(+), 19 deletions(-)

diff --git a/Adafruit_ADXL345.cpp b/Adafruit_ADXL345.cpp
index ad0b98c..c25ddd1 100644
--- a/Adafruit_ADXL345.cpp
+++ b/Adafruit_ADXL345.cpp
@@ -55,16 +55,44 @@ static void i2cwrite(uint8_t x) {
   #endif
 }
 
+
+
+
+/**************************************************************************/
+/*!
+    @brief  Abstract away SPI receiver & transmitter
+*/
+/**************************************************************************/
+static uint8_t spixfer(uint8_t clock, uint8_t miso, uint8_t mosi, uint8_t data) {
+  uint8_t reply = 0;
+  for (int i=7; i>=0; i--) {
+    reply <<= 1;
+    digitalWrite(clock, LOW);
+    digitalWrite(mosi, data & (1<<i));
+    digitalWrite(clock, HIGH);
+    if (digitalRead(miso)) 
+      reply |= 1;
+  }
+  return reply;
+}
+
 /**************************************************************************/
 /*!
     @brief  Writes 8-bits to the specified destination register
 */
 /**************************************************************************/
-static void writeRegister(uint8_t reg, uint8_t value) {
-  Wire.beginTransmission(ADXL345_ADDRESS);
-  i2cwrite((uint8_t)reg);
-  i2cwrite((uint8_t)(value));
-  Wire.endTransmission();
+void  Adafruit_ADXL345::writeRegister(uint8_t reg, uint8_t value) {
+  if (_i2c) {
+    Wire.beginTransmission(ADXL345_ADDRESS);
+    i2cwrite((uint8_t)reg);
+    i2cwrite((uint8_t)(value));
+    Wire.endTransmission();
+  } else {
+    digitalWrite(_cs, LOW);
+    spixfer(_clk, _di, _do, reg);
+    spixfer(_clk, _di, _do, value);
+    digitalWrite(_cs, HIGH);
+  }
 }
 
 /**************************************************************************/
@@ -72,12 +100,21 @@ static void writeRegister(uint8_t reg, uint8_t value) {
     @brief  Reads 8-bits from the specified register
 */
 /**************************************************************************/
-static uint8_t readRegister(uint8_t reg) {
-  Wire.beginTransmission(ADXL345_ADDRESS);
-  i2cwrite(reg);
-  Wire.endTransmission();
-  Wire.requestFrom(ADXL345_ADDRESS, 1);
-  return (i2cread());  
+uint8_t Adafruit_ADXL345::readRegister(uint8_t reg) {
+  if (_i2c) {
+    Wire.beginTransmission(ADXL345_ADDRESS);
+    i2cwrite(reg);
+    Wire.endTransmission();
+    Wire.requestFrom(ADXL345_ADDRESS, 1);
+    return (i2cread());
+  } else {
+    reg |= 0x80; // read byte
+    digitalWrite(_cs, LOW);
+    spixfer(_clk, _di, _do, reg);
+    uint8_t reply = spixfer(_clk, _di, _do, 0xFF);
+    digitalWrite(_cs, HIGH);
+    return reply;
+  }
 }
 
 /**************************************************************************/
@@ -85,12 +122,22 @@ static uint8_t readRegister(uint8_t reg) {
     @brief  Reads 16-bits from the specified register
 */
 /**************************************************************************/
-static int16_t read16(uint8_t reg) {
-  Wire.beginTransmission(ADXL345_ADDRESS);
-  i2cwrite(reg);
-  Wire.endTransmission();
-  Wire.requestFrom(ADXL345_ADDRESS, 2);
-  return (uint16_t)(i2cread() | (i2cread() << 8));  
+int16_t  Adafruit_ADXL345::read16(uint8_t reg) {
+  if (_i2c) {
+    Wire.beginTransmission(ADXL345_ADDRESS);
+    i2cwrite(reg);
+    Wire.endTransmission();
+    Wire.requestFrom(ADXL345_ADDRESS, 2);
+    return (uint16_t)(i2cread() | (i2cread() << 8));  
+  } else {
+    reg |= 0x80 | 0x40; // read byte | multibyte
+    digitalWrite(_cs, LOW);
+    spixfer(_clk, _di, _do, reg);
+    uint16_t reply = spixfer(_clk, _di, _do, 0xFF)  | (spixfer(_clk, _di, _do, 0xFF) << 8);
+    digitalWrite(_cs, HIGH);
+    return reply;
+
+  }
 }
 
 /**************************************************************************/
@@ -99,6 +146,15 @@ static int16_t read16(uint8_t reg) {
 */
 /**************************************************************************/
 Adafruit_ADXL345::Adafruit_ADXL345() {
+  _i2c = true;
+}
+
+Adafruit_ADXL345::Adafruit_ADXL345(uint8_t clock, uint8_t miso, uint8_t mosi, uint8_t cs) {
+  _cs = cs;
+  _clk = clock;
+  _do = mosi;
+  _di = miso;
+  _i2c = false;
 }
 
 /**************************************************************************/
@@ -107,8 +163,15 @@ Adafruit_ADXL345::Adafruit_ADXL345() {
 */
 /**************************************************************************/
 void Adafruit_ADXL345::begin() {
-  Wire.begin();
-  
+  if (_i2c)
+    Wire.begin();
+  else {
+    pinMode(_cs, OUTPUT);
+    pinMode(_clk, OUTPUT);
+    digitalWrite(_clk, HIGH);
+    pinMode(_do, OUTPUT);
+    pinMode(_di, INPUT);
+  }
   // Enable measurements
   writeRegister(ADXL345_REG_POWER_CTL, 0x08);  
 }
diff --git a/Adafruit_ADXL345.h b/Adafruit_ADXL345.h
index 19f348f..295b82a 100644
--- a/Adafruit_ADXL345.h
+++ b/Adafruit_ADXL345.h
@@ -69,11 +69,18 @@
 class Adafruit_ADXL345{
  public:
   Adafruit_ADXL345();
+  Adafruit_ADXL345(uint8_t clk, uint8_t miso, uint8_t mosi, uint8_t cs);
   void begin(void);
   uint8_t getDeviceID(void);
   int16_t getX(void);
   int16_t getY(void);
   int16_t getZ(void);
 
+  uint8_t readRegister(uint8_t reg);
+  void writeRegister(uint8_t reg, uint8_t value);
+  int16_t read16(uint8_t reg);
+
  private:
+  boolean _i2c;
+  uint8_t _clk, _do, _di, _cs;
 };